Wonderpark Two Pack of UltraSonic Dog Training Whistles - Ultimate Whistle to Stop Barking - Best Silent Dog Whistles--Training Tips for Your Dog+E-BOOK(Send In PDF Format Through e-mail) Send In PDF Format Through e-mail,100% Brand new. Training Whistles X 2.Color: Silver. Material: Brass. Length: 5.5cm(approx.) Designed in a key form, small and easy to carry around. Operating Range up to 200m.Pet Dog Training Obedience Adjustable Ultra Sonic Sound Whistle Noise New. This lightweight, compact whistle is ideal for dog training, both indoors and out. Distract your dog from their barking spree and distract them from whatever is causing the barking or other unwanted behavior.